1. Field of the Invention
This invention relates generally to office equipment, and more specifically, to an improved method and apparatus for removing a fastened staple from a stack of sheet goods.
2. Description of the Prior Art
Staple removing devices have long been known in the art. Their construction has been dictated to some extent by the properties and methods of use of the staple itself. Staples that are continuously driven into a substrate and which are used to retainably hold another article to the substrate (such as fencing staples) use the frictional force of their embedded legs to fasten the staple to the substrate. Such staples must by necessity be removed by pulling the staple legs out of the substrate by means of the crossbar member portion of the staple. A plier-type of staple remover or a specially designed hammer claw has generally been used for such purposes. Both such removal devices grasp the staple crossbar and then generally use the solid substrate itself as a fulcrum for providing leverage against the crossbar, to pull the staple legs out of the substrate.
Staples used for binding together sheet goods, such as paper, cannot generally be removed by those staple removers described above. The legs of a staple used for binding sheet goods pass through the sheet goods and are bent backwards toward the sheet goods so as to retainably bind or clinch the sheet goods between the bent legs and the crossbar. Since the sheet goods being bound are generally relatively thin and pliable (such as paper) they cannot be directly pried against by the staple remover or used for providing leverage in removing the staple, as is the case when a rigid substrate is used. Further, if one attempts to remove the staple by simply grasping the staple crossbar and pulling it away from the sheet goods, the bent or clinched legs of the staple will also pull through the sheet goods in their bent position, tearing the sheet goods in the process. In order to prevent damage to the sheet goods in the removal process, the staple remover must straighten the clinched legs so they can be longitudinally pulled or pushed through the sheet goods, generally in the opposite direction through which they originally entered the sheet goods.
While a number of staple remover configurations for removing staples binding sheet goods have been developed over the years, the most commonly used such device today employs a pair of opposed lever arms having facing curved claw members that cooperatively engage and lift the staple crossbar member from a position directly below and between the crossbar and the sheet goods on which it rests. This staple removing device, which for simplicity will hereinafter be referred to as to the "standard" staple remover, requires the operator to apply force to the pair of lever arms at positions generally overlying the claw members such that any mechanical advantage of the device's lever arms is negated. Also, the standard staple remover operates totally from one side of the sheet goods (i.e. the side on which the staple crossbar is disposed). The standard staple remover transmits forces for bending or straightening the clinched staple legs through the sheet goods, from positions directly underlying the staple crossbar. The underside of the crossbar itself is used by the remover claw members as the reactive surface from which straightening forces are transmitted through the sheet goods as the members are squeezed together to lift the crossbar away from the sheet goods.
One problem associated with the standard staple remover concerns its use in removing heavy duty staples and staples fastening large stacks of sheet goods. In such cases, due to the lack of any significant mechanical advantage of the standard staple remover, an operator generally simply engages the staple crossbar with the opposed claw members and "pulls" the staple through the sheet goods, relying on the strength of the combined sheet goods to provide the required reactive force for straightening the clinched legs of the staple. The standard staple remover is not designed to handle such "heavy-duty" applications. When used for such applications, it is often difficult for the operator of the staple remover to hold and pull the staple crossbar with sufficient force to cause the clinched legs of a heavy duty staple to sufficiently straighten, so that the staple may be pulled through the stack of sheet goods. Also, with a large stack of sheet goods, it is often the case that one leg of the staple will be removed while the other leg remains clinched or retainably held by the sheet goods. Thus, it is desirable to have a staple remover that does not require excessive operator force to straighten a heavy duty staple or to remove a staple from a thick stack of sheet goods. Furthermore, it is desirable to have a staple remover that consistently straightens both clinched legs of a heavy duty staple, so that both legs of the staple may be consistently pulled through the stack of sheet goods.
A second commonly encountered problem with the standard staple remover concerns its use on staples that have been machine-fastened, as occurs when automatic staplers and/or copying machines are used. Staples applied by these devices tend to be more tightly clinched, making it more difficult to straighten the clinched legs by simply applying a removal force to the staple crossbar from one side of the sheet goods. Thus, it is desirable to have a staple remover that consistently and effectively straightens the clinched legs of a machine-fastened staple, so that it can be more readily removed.
Yet another problem associated with the standard staple remover is that the remover does not positively secure the sheet goods separate from the staple during the removal process. As discussed above, the movable claw members of the standard staple remover cooperatively slide under the staple crossbar, simultaneously providing opposing forces between the lower side of the staple crossbar and the upper surface of the sheet goods upon which the crossbar rests. The claw surfaces engaging the surface of the sheet goods frictionally slide against the sheet good surface as the claws are squeezed together below the staple crossbar member. The sliding friction proportionately increases and the reaction force from the lower side of the staple crossbar increases as the claw members move toward one another. Such frictional sliding motion often results in physical tearing or ripping of the engaged sheet goods during the removal process.
Therefore, while the standard staple remover is well known and widely used, it does not satisfy many of the desired design attributes required of a staple remover that must operate in significantly different applications in the commercial/business environment. The present invention addresses most of the shortcomings of the prior art staple removers and, in particular, of the well known standard staple remover discussed above. The present invention provides a method and an apparatus for cooperatively clamping a stack of sheet goods that is bound by a staple, for substantially straightening the clinched legs of the staple, and for removing the staple by pulling the substantially straightened legs through the sheet goods with minimal operator effort and minimal damage to the sheet goods.